To solve accessibility problems of statistic websites, there are a project (for example, Social Accessibility (SA, http: //sa.watson.ibm.com/)) and a system (for example, Web Accessibility Improvement System (WAIS, http: //waisdistr1.tori-info.co.jp/)) to create external metadata with the assistance of a social network and to apply it. The workflow thereof will be described herein taking the SA as an example. As shown in FIG. 1, (1) when a user 60 encounters an inaccessible Web page, (2) the user 60 first reports a problem on the Web page to a social accessibility server 65, (3) then, the social accessibility server 65 that has received the report notifies a volunteer (supporter) 70 of the problem on the Web page, and the supporter 70 confirms the notified problem on the Web page with a browser, (4) Next, the supporter 70 corrects the problem on the Web page to create metadata and sends the metadata to the social accessibility server 65, (5) finally, the user 60 browses the Web page that read the corresponding metadata from the social accessibility server 65 and is corrected using the metadata to become accessible.
The structure of the metadata that the supporter 70 creates is defined in Non-patent Literature 1 as follows:    Uniform resource identifier (URI) address: a target URI that identifies a document to which the metadata is applied    Element address: a description of HTML element to which the metadata is applied (for example, XPath)    Condition: metadata application condition    Semantics: the meaning of the metadata
Techniques for applying correction information, such as metadata, to another problem are disclosed in Patent Literatures 1 to 3 and Non-patent Literature 2.
Patent Literature 1 discloses that the URI pattern is expressed by a URI including a wild card or a regular expression and that the pointer is expressed by XPath or a URI (also including a wild card or a regular expression) for indicating an image. Patent Literature 1 also discloses, as a method for extending metadata between pages, a technique for selecting metadata having the same data in a certain page, selecting analogized elements by generalizing Xpath of a plurality of items of metadata, and further selecting an element from the selected elements by using effect verification similarity and a preset threshold value. Patent Literature 1 also discloses, as a method for extending metadata between pages, a technique of selecting a page that can be evaluated in the other pages for XPath of given metadata, selecting elements to which the metadata is applicable in the selected page, and further selecting an element from the selected elements by using effect verification similarity and a preset threshold value.
Patent Literature 2 discloses a technique of accumulating results of diagnosis by a human whether accessibility of a Web page is suitable, and if the same design is found next time, showing the result of diagnosis on the basis of the previous diagnosis.
Patent Literature 3 discloses a technique of associating the description of conversion to content constituent elements of annotation data with the layout of this content constituent elements by using XPath and selecting an annotation file by determining whether the XPath can be applied to the Web content, that is, whether correct XPath is used for a group (a visual semantic block expressed in layout, such as a header, footer, link list, body, advertisement, and Web content background color) in the Web content. Patent Literature 3 further points out that the related art using a regular expression of an URL cannot cope with a case where Web content dynamically changes in layout by using a cookie or the like.
Non-patent Literature 2 discloses a technique for creating a general-purpose XPath by comparing a pair of XPaths in the viewpoint of attributes including id-expression, tag name, and index and by extracting the maximum commonality.
Patent Literature 4 is a document related to a technique for dynamically analyzing a state transition in a Web pate using DHTML, which discloses that the value of a global variable (variable defined for the entire program) in a java (a registered trademark) script can be used to acquire the state of the Web page.